Pilot test study on the performance of multiphase flow pump DAF equipment and reservoir water pollution removal by the DAF process

Abstract

The eutrophication of reservoir water leads to the proliferation of algae, the DAF process can overcome the lack of algae removal capacity in conventional treatment processes, and its pollution removal efficiency is affected by the equipment performance. Among DAF equipment, multiphase flow pumps have attracted attention because of their simple configuration and low failure rate. This paper studied the equipment performance and pollution removal efficiency of a multiphase flow pump for DAF. The results showed that the dissolution efficiency of the equipment was approximately 55% and the average particle size of bubbles was less than 26 μm. When the pressure was greater than 0.36 MPa, the bubble stability time exceeded 4 min. The optimal working conditions were achieved at a dissolved gas pressure of 0.4 MPa. The maximum removal rates of turbidity, chlorophyll a, TOC, UV254 and CODMn by the DAF process were 56.49%, 50.23%, 23.73%, 28.75% and 23.98%, respectively. The trend in pollution removal efficiency was consistent with that of equipment performance parameters. The surface of the microbubbles was hydrophobic and could more easily adsorb high-molecular-weight organic substances with strong hydrophobicity and algae with strongly hydrophobic colloidal layers inside. In addition, regarding the THMFP, the experimental results showed that the removal rates of the precursors CHCl3, CHBrCl2 and CHBr2Cl after DAF were 28.93%, 23.26% and 21.53%, respectively. Surface hydrophobicity is one of the main mechanisms by which microbubbles adhere to pollutants.